Many types of electrochemical cells utilize a liquid ionically conductive medium to support electrochemical reactions within the cell. For example, a metal-air electrochemical cell system may comprise a plurality of cells, each having a fuel electrode serving as an anode at which metal fuel is oxidized, and an air breathing oxidant reduction electrode at which oxygen from ambient air is reduced. The liquid ionically conductive medium in such cells may communicate the oxidized/reduced ions between the electrodes.
In some electrochemical cell systems utilizing a liquid ionically conductive medium, a flow pump is provided to circulate the ionically conductive medium either within a single cell or among a plurality of cells, so as to permit movement of reducible fuel species in the ionically conductive medium past reduction sites on the fuel electrode, so that the reducible fuel species may be plated as metal fuel on the fuel electrode during charging. Other benefits of the movement of ionically conductive medium are also possible, including but not limited to movement of oxidized species during discharge away from the anode, improving discharge kinetics; the removal of oxygen gas during charging from so-called three-electrode metal-air cells; and the prevention of stratification of the ionically conductive medium. In some electrochemical cell systems, utilizing such flow pumps greatly increases the complexity and size of the system. For example, the use of a flow pump may necessitate or otherwise make desirable fluidly joining multiple cells in a common flow path. Accordingly, in some such cell systems, utilizing a flow pump adds the increased size and expense of not only the flow pump itself, but also may require manifolds, pipes, and a reservoir, so as to connect multiple cells into the flow of the ionically conductive medium. In some cell systems, quick disconnects are provided to facilitate rapid disconnection and reconnection of individual cells or sets of cells from the cell system, such as for repair or replacement, whereby the quick disconnects are utilized to form sufficiently strong seals to prevent loss of ionically conductive medium through the connection points. Additionally, because the sharing of ionically conductive medium between multiple cells may result in a shunt current through the ionically conductive medium, some cell systems, such as those described in U.S. patent application Ser. No. 13/362,775, incorporated herein in its entirety by reference, may include flow dispersing showerheads that physically separate the ionically conductive medium in the flow between the cells, to prevent electrical conductivity through the ionically conductive medium from one cell to another.
One approach to facilitating a flow of ionically conductive medium in a cell is through bubbling of a gas through the cell, so as to create a lifting action by the rising gas in the liquid ionically conductive medium. An example of such an approach is disclosed in U.S. Pat. No. 5,011,747.
For reasons such as, but not limited to, making redundant or obviating the inclusion of the appurtenant features in the electrochemical cell system described above, it may be appreciated that cell systems utilizing a self contained cell configuration may be smaller, lighter, have fewer potential points of failure, and may be less expensive than prior configurations. Among other improvements, the present application endeavors to provide such an effective and improved electrochemical cell that further facilitates establishment of an improved flow of the ionically conductive medium utilizing the lifting action of a rising gas.